The present invention relates to a mechanical warp stop motion apparatus which acts to stop the operation of the associated weaving machine in case of warp end breakage, and more particularly to a mechanical warp stop device which utilizes multiple drop wire bars consisting of stationary outer serrated bars and movable inner serrated bars, the inner serrated bars being oscillated with respect to the associated outer serrated bars.
Due to lack of space, the large number of warp ends and the corresponding number of drop wires in a weaving machine cannot be arranged on one row. The drop wires therefore have to be arranged in several rows, running parallel to each other, and the parallel serrated bars of the associated mechanical warp stop motion device will be lined up therewith. As an example, with six serrated bars in the mechanical warp stop motion device, six rows of drop wires will also be used and each of these drop wires will, at the time of a warp end breakage, be capable of activating the mechanical warp stop motion device to in turn stop the weaving machine.
Existing warp stop motion devices of this nature, using for instance six serrated bars, utilize one common spring acting on all six serrated bars. The resisting force of this spring, which blocks the movement of one of the oscillating inner serrated bars and which has to be overcome in case of a warp end breakage and the subsequent falling of the drop wire, can be altered only by adjustment to that one spring. Due to the continuous drive which causes the oscillating movement, the spring, which co-operates with a coupling piece, will activate a contact, thus stopping the weaving machine. However, the resisting force of the spring has to be set relatively high so that the frictional force produced by the six serrated bars does not exceed the force of the spring, which otherwise will give false stoppages of the weaving machine. The pressure of the spring, on the other hand, has to be set stronger when the inner serrated bars are tightly fitted or when the dirt accumulation is heavy. The result of this is that the drop wires will get damaged or crushed on account of being pressed against the outer stationary serrated bar, and only after overcoming the pressure of the spring will the coupling piece discontinue driving the oscillating inner serrated bar and cause the weaving machine to be stopped. The drive is taken from a suitable mechanism which is part of the weaving machine.
It is an object of the present invention to provide a mechanical warp stop motion apparatus which will prevent the damage to the drop wires caused in the known prior art devices.